/**
 * @file
 * lwIP Operating System abstraction
 *
 */

/*
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Adam Dunkels <adam@sics.se>
 *
 */

#include "lwip/opt.h"

#if (NO_SYS == 0) /* don't build if not configured for use in lwipopts.h */

#include "lwip/sys.h"
#include "lwip/def.h"
#include "lwip/memp.h"
#include "lwip/tcpip.h"

/**
 * Struct used for sys_sem_wait_timeout() to tell wether the time
 * has run out or the semaphore has really become available.
 */
struct sswt_cb {
	s16_t timeflag;
	sys_sem_t* psem;
};

/**
 * Wait (forever) for a message to arrive in an mbox.
 * While waiting, timeouts (for this thread) are processed.
 *
 * @param mbox the mbox to fetch the message from
 * @param msg the place to store the message
 */
void
sys_mbox_fetch(sys_mbox_t mbox, void** msg)
{
	u32_t time_needed;
	struct sys_timeouts* timeouts;
	struct sys_timeo* tmptimeout;
	sys_timeout_handler h;
	void* arg;

again:
	timeouts = sys_arch_timeouts();

	if(!timeouts || !timeouts->next) {
		UNLOCK_TCPIP_CORE();
		time_needed = sys_arch_mbox_fetch(mbox, msg, 0);
		LOCK_TCPIP_CORE();
	} else {
		if(timeouts->next->time > 0) {
			UNLOCK_TCPIP_CORE();
			time_needed = sys_arch_mbox_fetch(mbox, msg, timeouts->next->time);
			LOCK_TCPIP_CORE();
		} else {
			time_needed = SYS_ARCH_TIMEOUT;
		}

		if(time_needed == SYS_ARCH_TIMEOUT) {
			/* If time == SYS_ARCH_TIMEOUT, a timeout occured before a message
			   could be fetched. We should now call the timeout handler and
			   deallocate the memory allocated for the timeout. */
			tmptimeout = timeouts->next;
			timeouts->next = tmptimeout->next;
			h   = tmptimeout->h;
			arg = tmptimeout->arg;
			memp_free(MEMP_SYS_TIMEOUT, tmptimeout);

			if(h != NULL) {
				LWIP_DEBUGF(SYS_DEBUG, ("smf calling h=%p(%p)\n", *(void**)&h, arg));
				h(arg);
			}

			/* We try again to fetch a message from the mbox. */
			goto again;
		} else {
			/* If time != SYS_ARCH_TIMEOUT, a message was received before the timeout
			   occured. The time variable is set to the number of
			   milliseconds we waited for the message. */
			if(time_needed < timeouts->next->time) {
				timeouts->next->time -= time_needed;
			} else {
				timeouts->next->time = 0;
			}
		}
	}
}

/**
 * Wait (forever) for a semaphore to become available.
 * While waiting, timeouts (for this thread) are processed.
 *
 * @param sem semaphore to wait for
 */
void
sys_sem_wait(sys_sem_t sem)
{
	u32_t time_needed;
	struct sys_timeouts* timeouts;
	struct sys_timeo* tmptimeout;
	sys_timeout_handler h;
	void* arg;

again:

	timeouts = sys_arch_timeouts();

	if(!timeouts || !timeouts->next) {
		sys_arch_sem_wait(sem, 0);
	} else {
		if(timeouts->next->time > 0) {
			time_needed = sys_arch_sem_wait(sem, timeouts->next->time);
		} else {
			time_needed = SYS_ARCH_TIMEOUT;
		}

		if(time_needed == SYS_ARCH_TIMEOUT) {
			/* If time == SYS_ARCH_TIMEOUT, a timeout occured before a message
			  could be fetched. We should now call the timeout handler and
			  deallocate the memory allocated for the timeout. */
			tmptimeout = timeouts->next;
			timeouts->next = tmptimeout->next;
			h = tmptimeout->h;
			arg = tmptimeout->arg;
			memp_free(MEMP_SYS_TIMEOUT, tmptimeout);

			if(h != NULL) {
				LWIP_DEBUGF(SYS_DEBUG, ("ssw h=%p(%p)\n", *(void**)&h, (void*)arg));
				h(arg);
			}

			/* We try again to fetch a message from the mbox. */
			goto again;
		} else {
			/* If time != SYS_ARCH_TIMEOUT, a message was received before the timeout
			   occured. The time variable is set to the number of
			   milliseconds we waited for the message. */
			if(time_needed < timeouts->next->time) {
				timeouts->next->time -= time_needed;
			} else {
				timeouts->next->time = 0;
			}
		}
	}
}

/**
 * Create a one-shot timer (aka timeout). Timeouts are processed in the
 * following cases:
 * - while waiting for a message using sys_mbox_fetch()
 * - while waiting for a semaphore using sys_sem_wait() or sys_sem_wait_timeout()
 * - while sleeping using the inbuilt sys_msleep()
 *
 * @param msecs time in milliseconds after that the timer should expire
 * @param h callback function to call when msecs have elapsed
 * @param arg argument to pass to the callback function
 */
void
sys_timeout(u32_t msecs, sys_timeout_handler h, void* arg)
{
	struct sys_timeouts* timeouts;
	struct sys_timeo* timeout, *t;

	timeout = memp_malloc(MEMP_SYS_TIMEOUT);

	if(timeout == NULL) {
		LWIP_ASSERT("sys_timeout: timeout != NULL", timeout != NULL);
		return;
	}

	timeout->next = NULL;
	timeout->h = h;
	timeout->arg = arg;
	timeout->time = msecs;

	timeouts = sys_arch_timeouts();

	LWIP_DEBUGF(SYS_DEBUG, ("sys_timeout: %p msecs=%"U32_F" h=%p arg=%p\n",
	                        (void*)timeout, msecs, *(void**)&h, (void*)arg));

	if(timeouts == NULL) {
		LWIP_ASSERT("sys_timeout: timeouts != NULL", timeouts != NULL);
		return;
	}

	if(timeouts->next == NULL) {
		timeouts->next = timeout;
		return;
	}

	if(timeouts->next->time > msecs) {
		timeouts->next->time -= msecs;
		timeout->next = timeouts->next;
		timeouts->next = timeout;
	} else {
		for(t = timeouts->next; t != NULL; t = t->next) {
			timeout->time -= t->time;

			if(t->next == NULL || t->next->time > timeout->time) {
				if(t->next != NULL) {
					t->next->time -= timeout->time;
				}

				timeout->next = t->next;
				t->next = timeout;
				break;
			}
		}
	}
}

/**
 * Go through timeout list (for this task only) and remove the first matching
 * entry, even though the timeout has not triggered yet.
 *
 * @note This function only works as expected if there is only one timeout
 * calling 'h' in the list of timeouts.
 *
 * @param h callback function that would be called by the timeout
 * @param arg callback argument that would be passed to h
*/
void
sys_untimeout(sys_timeout_handler h, void* arg)
{
	struct sys_timeouts* timeouts;
	struct sys_timeo* prev_t, *t;

	timeouts = sys_arch_timeouts();

	if(timeouts == NULL) {
		LWIP_ASSERT("sys_untimeout: timeouts != NULL", timeouts != NULL);
		return;
	}

	if(timeouts->next == NULL) {
		return;
	}

	for(t = timeouts->next, prev_t = NULL; t != NULL; prev_t = t, t = t->next) {
		if((t->h == h) && (t->arg == arg)) {
			/* We have a match */
			/* Unlink from previous in list */
			if(prev_t == NULL) {
				timeouts->next = t->next;
			} else {
				prev_t->next = t->next;
			}

			/* If not the last one, add time of this one back to next */
			if(t->next != NULL) {
				t->next->time += t->time;
			}

			memp_free(MEMP_SYS_TIMEOUT, t);
			return;
		}
	}

	return;
}

/**
 * Timeout handler function for sys_sem_wait_timeout()
 *
 * @param arg struct sswt_cb* used to signal a semaphore and end waiting.
 */
static void
sswt_handler(void* arg)
{
	struct sswt_cb* sswt_cb = (struct sswt_cb*) arg;

	/* Timeout. Set flag to TRUE and signal semaphore */
	sswt_cb->timeflag = 1;
	sys_sem_signal(*(sswt_cb->psem));
}

/**
 * Wait for a semaphore with timeout (specified in ms)
 *
 * @param sem semaphore to wait
 * @param timeout timeout in ms (0: wait forever)
 * @return 0 on timeout, 1 otherwise
 */
int
sys_sem_wait_timeout(sys_sem_t sem, u32_t timeout)
{
	struct sswt_cb sswt_cb;

	sswt_cb.psem = &sem;
	sswt_cb.timeflag = 0;

	/* If timeout is zero, then just wait forever */
	if(timeout > 0) {
		/* Create a timer and pass it the address of our flag */
		sys_timeout(timeout, sswt_handler, &sswt_cb);
	}

	sys_sem_wait(sem);

	/* Was it a timeout? */
	if(sswt_cb.timeflag) {
		/* timeout */
		return 0;
	} else {
		/* Not a timeout. Remove timeout entry */
		sys_untimeout(sswt_handler, &sswt_cb);
		return 1;
	}
}

/**
 * Sleep for some ms. Timeouts are processed while sleeping.
 *
 * @param ms number of milliseconds to sleep
 */
void
sys_msleep(u32_t ms)
{
	sys_sem_t delaysem = sys_sem_new(0);

	sys_sem_wait_timeout(delaysem, ms);

	sys_sem_free(delaysem);
}


#endif /* NO_SYS */
